1 Chapter 13: Acute suppurative otitis media and acute mastoiditis ...

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second year of life, by a downward growth of bone. When complete, at puberty, the stylomastoid foramen and facial nerve are then much more deeply placed on the inferior aspect of the skull deep to, and just anterior to, the mastoid process. The mastoid antrum The mastoid antrum is fully formed at birth but, as the mastoid process has not developed, it is very superficial, about 2 mm deep to the bony surface. It reaches the adult depth of about 15 mm at puberty. Thus, between infancy and puberty the antrum acquires an increased bony covering at the rate of approximately 1 mm per annum. The mastoid air cells Pneumatization of the mastoid bone occurs at the same time as the development of the mastoid process. Resorption of haemopoietic marrow occurs and, at the same time, mucous membrane from the antrum grows into the bony spaces so formed to line them, forming a complex system of interlinked air cells. Persistent infection of the bony framework of these air spaces constitutes the clinical entity of acute mastoiditis. In a small percentage of individuals, pneumatization does not take place, so although the mastoid antrum is always present, the mastoid bone is acellular and of 'ivory' type, and these patients do not develop acute mastoiditis. Intermediate types also occur, either as normal variants, or due to arrest of pneumatization by childhood ear infections. The tympanic membrane The tympanic membrane is fully formed at birth but is more horizontally placed, making access for myringotomy difficult. Along with the developments outlined above, it gradually assumes a more vertical plane. Acute suppurative otitis media Aetiology Route of infection By way of the eustachian tube The relative incompetence of the eustachian tube in younger children is referred to above. The vast majority of infecting organisms reach the middle ear by way of the eustachian tube in both children and adults, most commonly from an ordinary head cold. Even after the eustachian tube reaches its adult, more protective, form, infection still reaches the middle ear by direct spread along the mucosa, or infected mucus can be propelled into the middle ear by forcible nose-blowing, sneezing, pressure changes as in flying, and forcing water up the nose as in jumping into swimming pools. 2
By way of the tympanic membrane The route can be by way of the tympanic membrane, either due to a pre-existing perforation, when infected material may enter the middle ear during hair-washing, facewashing and swimming; due to a traumatic perforation by an unsterile object; or due to operative trauma, for example, myringotomy, tympanotomy, or through a ventilation tube. Blood-borne infection It is thought that some viral infections of the middle ear, including the acute specific fevers and influenza, may be blood-borne. While this chapter is concerned with acute suppurative otitis media and hence with pyogenic infection, pyococci frequently follow and invade tissues already affected by viruses. Age Acute suppurative otitis media is a common disease of childhood, with about five children in every 100 having at least one attack in their first 10 years (Lewis et al, 1967). The peak incidence is sometimes stated to be from 5 to 7 years, after which it declines rapidly. However, several studies have shown that the incidence is highest among preschool children, especially before the second birthday. In one such study of a population of 146822 of all ages living in various parts of Finland, about 50% of all cases of acute suppurative otitis media were found in infants under 2 years old (Pukander et al, 1982). The annual incidence in this study was 4.4%. Sex According to Bordley, Brookhouser and Tucker (1986) 60-65% of otitis media cases in children are males. The Finnish study referred to above showed that the annual attack rater was 4.84% in males and 4.07% in females. No rationale for this apparent inequality has been identified. Socio-economic factors The incidence is highest in low hygiene populations, and under conditions of overcrowding and malnutrition. Climate A higher incidence of acute suppurative otitis media is seen in cold climates, especially in winter. The incidence is also higher in urban areas than in the country. Racial factors Studies in the USA (Brodley, Brookhouser and Tucker, 1986) have shown a higher incidence of acute suppurative otitis media in white children compared with black; a particularly high incidence is seen in Eskimos and American Indians. 3
Page 1: Chapter 13: Acute suppurative otiti
Page 5 and 6: Immunodeficiency syndromes Immunode
Page 7 and 8: There may be a history of one or mo
Page 9 and 10: diminished by antibiotic treatment.
Page 11 and 12: Treatment of acute suppurative otit
Page 13 and 14: psychotic symptoms, especially in c
Page 15 and 16: pus in the air cells leads to necro
Page 17 and 18: Swelling over the mastoid bone may
Page 19 and 20: usually normal. Secondary bacterial
Page 21 and 22: The patient should be admitted to h
Page 23 and 24: lateral sinus should be exposed; if
Page 25: Eagleton's operation A wide exposur

1 Chapter 13: Acute suppurative otitis media and acute mastoiditis ...

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